Both the first generation and USB-C Apple Pencils can only be charged via direct connection. Neither can be charged wirelessly. As such, for your current iPad, you will be charging either Pencil using an appropriate USB cable/adapter arrangement.
From a practical perspective, the USB-C Pencil differs from the first generation Pencil in two key aspects:
1) The USB-C Pencil can be magnetically "docked" to the edge of a compatible iPad - whereas the first generation Pencil cannot be attached to the host iPad, for convenience, when it is not being used.
2) The USB-C Pencil does not support pressure sensitivity - whereas the first generation Pencil does offer this feature.
Ultimately, your choice of Pencil may be dictated by your personal preferences. For information, here is a feature comparison of all models of Apple Pencil (noting that only two are compatible with your iPad):
